1. Technical Field
This invention relates generally to de-lamination of two pieces of media which have been laminated together such as by the use of heat and/or pressure, and more particularly to the use of automatic means for guiding a de-lamination leader to a set of nip rollers to break the bond between the two pieces of laminated media and to peel apart the lamination.
2. Background Art
The KODAK Color Proofing Laminator is used to bond lamination sheets to receiver stock as a part of a color proofing system. The lamination sheets include a carrier and a layer of material to be applied to the receiver stock, which, in the case of Kodak Color Proofing Laminator, is a color donor. A lamination sheet is laid upon the receiver stock with the color donor side sandwiched between the carrier and the receiver stock.
As shown in FIG. 1, the leading edge of the lamination sheet and receiver stock sandwich 10 is fed into a laminator 12, and the sandwich passes completely through a set of heated rollers, not shown. The laminated sandwich sits on an exit table 14 undisturbed until the trailing edge is cool to the touch, whereupon the top-most carrier can be peeled away from receiver stock and from the transferred color donor. Further details of this type of lamination/de-lamination system can be found in commonly-assigned, U.S. Pat. No. 5,203,942, which issued to B. DeCook et al. on Apr. 20, 1993.
Peeling the carrier of this particular media before it is cool risks color donor "pick-off" from the receiver stock. That is, peeling too soon results in non-uniform transfer and the loss of highlight dots (dots of less than, say, 5% coverage) because the transferred materials do not have a chance to set up. Accordingly, the operator is instructed to allow sufficient time for the materials to cool down.
While the above-described KODAK Color Proofing Laminator works well for many intended materials, there are other materials that require peeling the carrier from the receiver stock while the sandwich is hot to prevent bonding between the carrier and the receiver stock. An operator would be required to quickly grasp the hot sandwich as it emerges from the roller, manually break the seal between the leading edge of the carrier and the receiver stock (such as with a thumb nail), and peel the carrier as the sandwich progresses from the rollers.
Because of the requirement to peel the media while it is still hot, and because of the fairly small window of time during which peeling may be effected without the risk of donor pick-off or bonding the carrier to the receiver stock, there is a need for an apparatus and method for automatically peeling the sandwich apart at the appropriate time after lamination.